Evolutionary divergence of subgenomes in common carp provides insights into speciation and allopolyploid success.

Hybridization and polyploidization have made great contributions to speciation, heterosis, and agricultural production within plants, but there is still limited understanding and utilization in animals. Subgenome structure and expression reorganization and cooperation post hybridization and polyploidization are essential for speciation and allopolyploid success. However, the mechanisms have not yet been comprehensively assessed in animals. Here, we produced a high-fidelity reference genome sequence for common carp, a typical allotetraploid fish species cultured worldwide. This genome enabled in-depth analysis of the evolution of subgenome architecture and expression responses. Most genes were expressed with subgenome biases, with a trend of transition from the expression of subgenome A during the early stages to that of subgenome B during the late stages of embryonic development. While subgenome A evolved more rapidly, subgenome B contributed to a greater level of expression during development and under stressful conditions. Stable dominant patterns for homoeologous gene pairs both during development and under thermal stress suggest a potential fixed heterosis in the allotetraploid genome. Preferentially expressing either copy of a homoeologous gene at higher levels to confer development and response to stress indicates the dominant effect of heterosis. The plasticity of subgenomes and their shifting of dominant expression during early development, and in response to stressful conditions, provide novel insights into the molecular basis of the successful speciation, evolution, and heterosis of the allotetraploid common carp.

Attentional bias toward pictures related to circumscribed interests in children with autism spectrum disorder.

Background: Circumscribed interests (CIs) are regarded as one of the common symptoms for individuals with autism spectrum disorder (ASD). Although some studies have found attentional bias toward CI-related stimuli for individuals with ASD, few studies have directly explored the reasons for these findings. Method: Children with ASD (n = 15) and age-matched typically developing (TD) children (n = 15) completed a Stroop-like task and a modified dot-probe task, and their reaction times were measured. The stimuli of these tasks included neutral objects and objects related to CI for individuals with ASD. Results: Children with ASD had longer reaction times to name colors of CI-related stimuli than neutral stimuli in the Stroop-like task. Similarly, in the modified dot-probe task, if the CI-related stimulus was presented simultaneously with the neutral stimulus, children with ASD responded faster to the target that appeared in the previous location of the CI-related stimulus (i.e. congruent condition) than to the neutral stimulus (i.e. incongruent condition). Importantly, the reaction times of children with ASD in the incongruent condition were significantly slower than in the baseline condition, where both neutral stimuli were displayed simultaneously with stimulus-onset asynchrony (SOA) of 500 ms. In contrast, there was no significant difference in reaction times to CI-related stimuli and neutral stimuli in both tasks for TD children. Conclusions: These findings suggest children with ASD have attentional bias toward CI-related stimuli, because of difficulty disengaging attention from CI-related stimuli with SOA of 500 ms.

Identification of benzothiazole derived monosaccharides as potent, selective, and orally bioavailable inhibitors of human and mouse galectin-3; a rare example of using a S···O binding interaction for drug design.

As a result of our continued efforts to pursue Gal-3 inhibitors that could be used to fully evaluate the potential of Gal-3 as a therapeutic target, two novel series of benzothiazole derived monosaccharides as potent (against both human and mouse Gal-3) and orally bioavailable Gal-3 inhibitors, represented by 4 and 5, respectively, were identified. These discoveries were made based on proposals that the benzothiazole sulfur atom could interact with the carbonyl oxygen of G182/G196 in h/mGal-3, and that the anomeric triazole moiety could be modified into an N-methyl carboxamide functionality. The interaction between the benzothiazole sulfur and the carbonyl oxygen of G196 in mGal-3 was confirmed by an X-ray co-crystal structure of early lead 9, providing a rare example of using a S···O binding interaction for drug design. It was found that for both the series, methylation of 3-OH in the monosaccharides caused no loss in h & mGal-3 potencies but significantly improved permeability of the molecules.

Contribution of elovl5a to Docosahexaenoic Acid (DHA) Synthesis at the Transcriptional Regulation Level in Common Carp, Cyprinus carpio.

Docosahexaenoic acid (DHA) is an essential nutrient for humans and plays a critical role in human development and health. Freshwater fish, such as the common carp (Cyprinus carpio), have a certain degree of DHA biosynthesis ability and could be a supplemental source of human DHA needs. The elongase of very-long-chain fatty acid 5 (Elovl5) is an important enzyme affecting polyunsaturated fatty acid (PUFA) biosynthesis. However, the function and regulatory mechanism of the elovl5 gene related to DHA synthesis in freshwater fish is not clear yet. Previous studies have found that there are two copies of the elovl5 gene, elovl5a and elovl5b, which have different functions. Our research group found significant DHA content differences among individuals in Yellow River carp (Cyprinus carpio var.), and four candidate genes were found to be related to DHA synthesis through screening. In this study, the expression level of elovl5a is decreased in the high-DHA group compared to the low-DHA group, which indicated the down-regulation of elovl5a in the DHA synthesis pathways of Yellow River carp. In addition, using a dual-luciferase reporter gene assay, we found that by targeting the 3'UTR region of elovl5a, miR-26a-5p could regulate DHA synthesis in common carp. After CRISPR/Cas9 disruption of elovl5a, the DHA content in the disrupted group was significantly higher than in the wildtype group; meanwhile, the expression level of elovl5a in the disrupted group was significantly reduced compared with the wildtype group. These results suggest that elovl5a may be down-regulating DHA synthesis in Yellow River carp. This study could provide useful information for future research on the genes and pathways that affect DHA synthesis.

A study of the use of virtual reality headsets in Chinese adolescents with intellectual disability.

Background: Virtual reality technologies (VRTs) present many characteristics that can facilitate learning, especially in individuals with intellectual disabilities (ID). The VRT head-mounted display (HMD) has recently shown significant technological improvement. This study aims to prove the suitability of the newer commercially available VRT HMDs used in interventions for adolescents with ID in China. To this end, we explored the acceptance, immersion, and negative effects for adolescents with ID in a series of virtual environments. Methods: Forty-nine adolescents with ID (33 boys and 16 girls, IQ < 70), aged 11 to 21, from three special schools participated in this study. Questionnaires, observations, and interviews were used to investigate their views while using a VR HMD. Results: Our analysis found that most participants narrated a pleasant experience using HMD and a series of VR experiences and experienced a high level of immersion accompanied by low negative effects. In addition, our study found that the gender variable was independent of the acceptance of HMDs and the immersion experience. Conclusions: Overall, this study suggests that the HMD is accepted by most Chinese adolescents with ID; thus, its application has great potential in China.

Manipulating the Reaction Pathway of CO2 Photoreduction via the Microenvironment of a Re Molecular Catalyst.

Re molecular complexes incorporated into two metal-organic frameworks were investigated to disclose the host-guest interaction by infrared and 1H nuclear magnetic resonance and to explore the microenvironment around the Re complex by absorption and photoluminescence spectra. ZIF-8 provides a confined space to isolated Re via an electrostatic interaction, while UiO-66 exerts a relaxed space to accessible Re via a coordination interaction. For CO2 two-electron photoreduction to CO, the turnover number of 28.6 in Re@ZIF-8 is 10-fold that of 2.7 in Re@UiO-66. The electron transfer is promoted in Re@ZIF-8 by a local electrostatic field with a cross-space pathway, whereas it is retarded in Re@UiO-66 as the solvation shell surrounding Re. In the following CO2 activation, the charged intermediate species could be stabilized in Re@ZIF-8 by spatial confinement, while Re-triethanolamine adducts prevailed in Re@UiO-66 with the accessibility of the Re complex. This work demonstrates a feasibility of diverting the CO2 activation pathway by the microenvironment of a molecular catalyst in the field of artificial photosynthesis.

Intercross population study reveals that co-mutation of mitfa genes in two subgenomes induces red skin color in common carp ( Cyprinus carpio wuyuanensis).

Common carp are among the oldest domesticated fish in the world. As such, there are many food and ornamental carp strains with abundant phenotypic variations due to natural and artificial selection. Hebao red carp (HB, Cyprinus carpio wuyuanensis), an indigenous strain in China, is renowned for its unique body morphology and reddish skin. To reveal the genetic basis underlying the distinct skin color of HB, we constructed an improved high-fidelity (HiFi) HB genome with good contiguity, completeness, and correctness. Genome structure comparison was conducted between HB and a representative wild strain, Yellow River carp (YR, C. carpio haematopterus), to identify structural variants and genes under positive selection. Signatures of artificial selection during domestication were identified in HB and YR populations, while phenotype mapping was performed in a segregating population generated by HB×YR crosses. Body color in HB was associated with regions with fixed mutations. The simultaneous mutation and superposition of a pair of homologous genes ( mitfa) in chromosomes A06 and B06 conferred the reddish color in domesticated HB. Transcriptome analysis of common carp with different alleles of the mitfa mutation confirmed that gene duplication can buffer the deleterious effects of mutation in allotetraploids. This study provides new insights into genotype-phenotype associations in allotetraploid species and lays a foundation for future breeding of common carp.

Research on Satellite Network Traffic Prediction Based on Improved GRU Neural Network.

The current satellite network traffic forecasting methods cannot fully exploit the long correlation between satellite traffic sequences, which leads to large network traffic forecasting errors and low forecasting accuracy. To solve these problems, we propose a satellite network traffic forecasting method with an improved gate recurrent unit (GRU). This method combines the attention mechanism with GRU neural network, fully mines the characteristics of self-similarity and long correlation among traffic data sequences, pays attention to the importance of traffic data and hidden state, learns the time-dependent characteristics of input sequences, and mines the interdependent characteristics of data sequences to improve the prediction accuracy. Particle Swarm Optimization (PSO) algorithm is used to obtain the best network model Hyperparameter and improve the prediction efficiency. Simulation results show that the proposed method has the best fitting effect with real traffic data, and the errors are reduced by 26.9%, 37.2%, and 57.8% compared with the GRU, Support Vector Machine (SVM), and Fractional Autoregressive Integration Moving Average (FARIMA) models, respectively.

Identification of Monosaccharide Derivatives as Potent, Selective, and Orally Bioavailable Inhibitors of Human and Mouse Galectin-3.

Galectin-3 (Gal-3), a member of the ß-galactoside-binding protein family, is implicated in a wide variety of human diseases. Identification of Gal-3 inhibitors with the right combination of potency (against both human and mouse Gal-3) and pharmacokinetic properties to fully evaluate the potential of Gal-3 for therapeutic intervention has been a major challenge due to the characteristics of its binding pocket: high hydrophilicity and key structural differences between human Gal-3 and the mouse ortholog. We report the discovery of a novel series of monosaccharide-based, highly potent, and orally bioavailable inhibitors of human and mouse Gal-3. The novel monosaccharide derivatives proved to be selective for Gal-3, the only member of the chimeric type of galectins, over Gal-1 and Gal-9, representative of the prototype and tandem-repeat type of galectins, respectively. The proposed binding mode for the newly identified ligands was confirmed by an X-ray cocrystal structure of a representative analogue bound to Gal-3 protein.

Changes in physiological responses and immunity of blunt snout bream Megalobrama amblycephala from transport stress.

This study aimed to investigate the effects of transport stress on the physiological responses and immunity of Megalobrama amblycephala (blunt snout bream). Fish (109.67 ± 1.51 g) were sampled at nine time points: before transport (control), at 0 h, 1 h, 3 h, 6 h, 12 h, 24 h, 3 days, and 7 days after 4 h of medium-distance transportation, and four fish were sampled in each time point. The results showed that plasma cortisol, triiodothyronine (T3), complement component 3 (C3), complement component 4 (C4), immunoglobulin M (IgM) and nitrogen monoxide (NO) concentrations, and alternative complement pathway (ACH50), acid phosphatase (ACP), and myeloperoxidase (MPO) activities all reached the peak at 0 h after transportation; C4 and NO concentrations as well as ACP and MPO activities returned to the control level after 1 h, ACH50 activity as well as cortisol, T3, and IgM concentration returned to the control level after 12 h, and C3 concentration returned to the control level after 24 h respectively. Plasma glucose and total protein concentrations as well as lysozyme activity all reached the peak at 1 h after transportation, total protein concentration and lysozyme activity returned to the control level after 3 h, and glucose concentration returned to the control level after 6 h (P < 0.05). Liver heat shock protein 70 expression reached the peak at 1 h after transportation, and returned to the control level after 24 h; liver heat shock protein 90 expression reached the peak at 0 h after transportation and returned to the control level after 12 h (P < 0.05). Overall, these findings suggested that 4 h of medium-distance transportation caused stress response of blunt snout bream, and transport stress had a significant effect on plasma indicators. But the recovery of 24 h after transport could return the physiological response, immune indexes, and the expression of heat shock protein to the normal level. This also provided data support for the medium-distance transportation of blunt snout bream in the future.

Satellite Network Task Deployment Method Based on SDN and ICN.

With the rapid development of 5G and the Internet of Things, satellite networks are emerging as an indispensable part of realizing wide-area coverage. The growth of the constellation of low-orbit satellites makes it possible to deploy edge computing services in satellite networks. This is, however, challenging due to the topological dynamics and limited resources of satellite networks. To improve the performance of edge computing in a satellite network, we propose a satellite network task deployment method based on SDN (software-defined network) and ICN (information-centric network). In this method, based on the full analysis of satellite network resources, a mission deployment model of a low-orbit satellite network is established. The genetic algorithm is then used to solve the proposed method. Experiments confirm that this method can effectively reduce the response delay of the tasks and the network traffic caused by task processing.

Deep Learning-Based Chest CT Image Features in Diagnosis of Lung Cancer.

This study was to evaluate the diagnostic value of deep learning-optimized chest CT in the patients with lung cancer. 90 patients who were diagnosed with lung cancer by surgery or puncture in hospital were selected as the research subjects. The Mask Region Convolutional Neural Network (Mask-RCNN) model was a typical end-to-end image segmentation model, and Dual Path Network (DPN) was used in nodule detection. The results showed that the accuracy of DPN algorithm model in detecting lung lesions in lung cancer patients was 88.74%, the accuracy of CT diagnosis of lung cancer was 88.37%, the sensitivity was 82.91%, and the specificity was 87.43%. Deep learning-based CT examination combined with serum tumor detection, factoring into Neurospecific enolase (N S E), cytokeratin 19 fragment (CYFRA21), Carcinoembryonic antigen (CEA), and squamous cell carcinoma (SCC) antigen, improved the accuracy to 97.94%, the sensitivity to 98.12%, and the specificity to 100%, all showing significant differences (P < 0.05). In conclusion, this study provides a scientific basis for improving the diagnostic efficiency of CT imaging in lung cancer and theoretical support for subsequent lung cancer diagnosis and treatment.

A pilot study of radiomics signature based on biparametric MRI for preoperative prediction of extrathyroidal extension in papillary thyroid carcinoma.

OBJECTIVE: To investigate efficiency of radiomics signature to preoperatively predict histological features of aggressive extrathyroidal extension (ETE) in papillary thyroid carcinoma (PTC) with biparametric magnetic resonance imaging findings. MATERIALS AND METHODS: Sixty PTC patients with preoperative MR including T2WI and T2WI-fat-suppression (T2WI-FS) were retrospectively analyzed. Among them, 35 had ETE and 25 did not. Pre-contrast T2WI and T2WI-FS images depicting the largest section of tumor were selected. Tumor regions were manually segmented using ITK-SNAP software and 107 radiomics features were computed from the segmented regions using the open Pyradiomics package. Then, a random forest model was built to do classification in which the datasets were partitioned randomly 10 times to do training and testing with ratio of 1:1. Furthermore, forward greedy feature selection based on feature importance was adopted to reduce model overfitting. Classification accuracy was estimated on the test set using area under ROC curve (AUC). RESULTS: The model using T2WI-FS image features yields much higher performance than the model using T2WI features (AUC = 0.906 vs. 0.760 using 107 features). Among the top 10 important features of T2WI and T2WI-FS, there are 5 common features. After feature selection, the models trained using top 2 features of T2WI and the top 6 features of T2WI-FS achieve AUC 0.845 and 0.928, respectively. Combining features computed from T2WI and T2WI-FS, model performance decreases slightly (AUC = 0.882 based on all features and AUC = 0.913 based on top features after feature selection). Adjusting hyper parameters of the random forest model have negligible influence on the model performance with mean AUC = 0.907 for T2WI-FS images. CONCLUSIONS: Radiomics features based on pre-contrast T2WI and T2WI-FS is helpful to predict aggressive ETE in PTC. Particularly, the model trained using the optimally selected T2WI-FS image features yields the best classification performance. The most important features relate to lesion size and the texture heterogeneity of the tumor region.

The allotetraploid origin and asymmetrical genome evolution of the common carp Cyprinus carpio.

Common carp (Cyprinus carpio) is an allotetraploid species derived from recent whole genome duplication and provides a model to study polyploid genome evolution in vertebrates. Here, we generate three chromosome-level reference genomes of C. carpio and compare to related diploid Cyprinid genomes. We identify a Barbinae lineage as potential diploid progenitor of C. carpio and then divide the allotetraploid genome into two subgenomes marked by a distinct genome similarity to the diploid progenitor. We estimate that the two diploid progenitors diverged around 23 Mya and merged around 12.4 Mya based on the divergence rates of homoeologous genes and transposable elements in two subgenomes. No extensive gene losses are observed in either subgenome. Instead, we find gene expression bias across surveyed tissues such that subgenome B is more dominant in homoeologous expression. CG methylation in promoter regions may play an important role in altering gene expression in allotetraploid C. carpio.

Patterns of Geographical and Potential Adaptive Divergence in the Genome of the Common Carp (Cyprinus carpio).

The common carp, Cyprinus carpio, is a cyprinid fish species cultured in Europe and Asia. It accounts for >70% of freshwater aquaculture production worldwide. We conducted a population genomics analysis on C. carpio using high-throughput SNP genotyping of 2,198 individuals from 14 populations worldwide to determine the genetic architecture of common carp populations and the genetic bases for environmental adaptation. Structure analyses including phylogeny and principal component analysis were also conducted, showing distinct geographical patterns in European and Asian populations. The linkage disequilibrium block average lengths of the 14 populations ranged from 3.94 kb to 36.67 kb. Genes within selective sweep regions were identified by genome scanning among the different populations, including gdf6a, bmpr1b, and opsin5. Gene Ontology and KEGG enrichment analyses revealed potential trait-related loci and genes associated with body shape, scaling patterns, and skin color. This population genomics analysis may provide valuable clues for future genome-assisted breeding of C. carpio.

Effects of dietary supplementation of three strains of Lactococcus lactis on HIFs genes family expression of the common carp following Aeromonas hydrophila infection.

HIFs (Hypoxia inducible factors) are the main regulators of the expression change of oxygen-dependent genes, in addition, they also play important roles in immune regulation. HIFs participate in infectious diseases and inflammatory responses, providing us a new therapeutic target for the treatment of diseases. In this study, 16 HIFs were identified in common carp genome database. Comparative genomics analysis showed large expansion of HIF gene family and approved the four round whole genome duplication (WGD) event in common carp. To further understand the function of HIFs, the domain architectures were predicted. All HIF proteins had the conserved HLH-PAS domain, which were essential for them to form dimer and bind to the downstream targets. The differences in domain of HIFα and HIFß might result in their different functions. Phylogenetic analysis revealed that all HIFs were divided into two subfamilies and the HIFs in common carp were clustered with their teleost counterparts indicating they are highly conservative during evolution. In addition, the tissue distribution was examined by RT-PCR showed that most of HIF genes had a wide range of tissue distribution but exhibited tissue-specific expression patterns. The expression divergences were observed between the copy genes, for example, HIF1A-1, HIF2A-1, ARNT-2 had wide tissue distribution while their copies had limited tissue distribution, proving the function divergence of copies post the WGD event. In order to find an effective activation of HIFs and apply to treatment of aquatic diseases, we investigate the dietary supplementation effects of different strains of Lactococcus lactis on the expression of HIFα subfamily members in kidney of common carp infected with A. hydrophila. In addition, all of the HIF genes have a high expression in the early stages of infection, and decreased in the treatment time point of 48 h in common carp. This phenomenon confirms that as a switch, the main function of HIFs is to regulate the production of immune response factors in early infection. So activation of the switch may be an effective method for infectious disease treatment. As expected, the treatment groups improved the expression of HIFs compared with the control group, and the effects of the three strains are different. The strain1 of L. lactis had a stronger induction on HIF genes than strain2 and strain3, and it might be applied as a potential activation of HIF genes for disease treatment. So, adding befitting L. lactis maybe a well method to activate the HIF genes to protect them from mycobacterial infection.

Glucose-6-phosphate dehydrogenase mutant D306C has a higher inhibition rate for enzyme multiplied immunoassay of cholyglycine.

Glucose-6-phosphate dehydrogenase (G6PDH) has been used in enzyme multiplied immunoassay technique (EMIT) assays for detecting small molecule metabolites such as cholyglycine (CG). A key parameter for successful EMIT CG assay development is the inhibition rate of the G6PDH-CG conjugate, measured as the decrease in enzyme activity upon CG antibody binding. Several commonly used G6PDH cysteine mutants including A45C and K55C have been labeled with CG-maleimide derivative, but inhibition rates of are unsatisfactory. Herein, we investigated whether other mutation sites can achieve better inhibition rates. We generated eight cysteine mutants (K106C, Y155C, A201C, T258C, D306C, D375C, G426C, and D480C) of G6PDH, measured their inhibition rates, and evaluated the performance of the D306C mutant using EMIT CG assays. One of the eight mutants (D306C) displayed improved inhibition rate, whereas all others exhibited inhibition similar to or lower than that of A45C and K55C. The enhanced inhibition rate of D306C improved the EMIT CG assay calibration curve, using an Abbott c16000 automated biochemical analyzer, resulting in better repeatability, precision, and linearity than with K55C assays and a commercially available EMIT CG kit. The G6PDH mutant D306C has a higher inhibition rate in EMIT CG assays and improves assay performance.

Genomic, Transcriptomic, and Epigenomic Features Differentiate Genes That Are Relevant for Muscular Polyunsaturated Fatty Acids in the Common Carp.

Polyunsaturated fatty acids (PUFAs) are a set of important nutrients that mainly include arachidonic acid (ARA4), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and α-linolenic acid (ALA). Recently, fish-derived PUFAs have been associated with cardiovascular health, fetal development, and improvement of brain functions. Studies have shown that fish muscular tissues are rich in PUFAs, which are influenced by various factors, including genetic variations, regulatory profiles, and methylation status of desaturase genes during fatty acid desaturation and elongation processes. However, the genetic mechanism and the pathways involved in fatty acid metabolism in fishes remain unclear. The overall aim of this study was to assess differences in gene expression responses among fishes with different fatty acid levels. To achieve this goal, we conducted genome-wide association analysis (GWAS) using a 250K SNP array in a population of 203 samples of common carp (Cyprinus carpio) and identified nine SNPs and 15 genes associated with muscular PUFA content. Then, RNA-Seq and whole genome bisulfite sequencing (WGBS) of different groups with high and low EPA, DHA, ARA4, and ALA contents in muscle, liver and brain tissues were conducted, resulting in 6,750 differentially expressed genes and 5,631 genes with differentially methylated promoters. Gene ontology and KEGG pathway enrichment analyses of RNA-Seq and WGBS results identified enriched pathways for fatty acid metabolism, which included the adipocytokine signaling pathway, ARA4 and linoleic acid metabolism pathway, and insulin signaling pathway. Integrated analysis indicated significant correlations between gene expression and methylation status among groups with high and low PUFA contents in muscular tissues. Taken together, these multi-level results uncovered candidate genes and pathways that are associated with fatty acid metabolism and paved the way for further genomic selection and carp breeding for PUFA traits.

Dataset on evolution analysis of splenic transcriptome in bighead carp and silver carp.

Bighead carp (Aristichthys nobilis) and silver carp (Hypophthalmichthys molitrix) are closely related species in the subfamily Xenocypridinae within Cyprinidae, and they are also two of the four most important pond-cultured fish species in China. The ability to resist some diseases often differs significantly in silver carp and bighead carp during fishery production. However, the evolutionary divergence of the immune defense functions in these two species is still not understood at the molecular level. The data presented in this article are related to the research article entitled "Comparative analysis of spleen transcriptome detects differences in evolutionary adaptation of immune defense functions in bighead carp and silver carp" (Li et al., 2018). Please refer to this data article for interpretation of the data. Data provided in this submission comprise the Ka/Ks ratios of orthologs as well as adaptive evolution genes, expression levels of orthologs, and TPM value of genes expressed only in spleen of bighead carp or silver carp. These data provide a better understanding of the differences in evolutionary adaptation of immune defense functions in bighead carp and silver carp.

Comparative analysis of spleen transcriptome detects differences in evolutionary adaptation of immune defense functions in bighead carp and silver carp.

The evolutionary divergence of the immune defense functions in bighead carp (A. nobilis) and silver carp (H. molitrix) is still not understood at the molecular level. Here, we obtained 48,821,754 and 55,054,480 clean reads from spleen tissue libraries prepared for bighead carp and silver carp using Illumina paired-end sequencing technology, respectively, and identified 4976 orthologous genes from the transcriptome data sets by comparative analysis. Adaptive evolutionary analysis showed that 212 orthologous genes and 255 Gene Ontology (GO) terms were subjected to positive selection(Ka/Ks values > 1) only in bighead carp, and 195 orthologous genes and 309 GO terms only in silver carp. Among immune defense functions with significant evolutionary divergence, the positively selected biological processes in bighead carp mainly included B cell-mediated immunity, chemokine-mediated signaling pathway, and immunoglobulin mediated immune response, whereas those in silver carp mainly included the antigen processing and presentation, defense response to fungus, and detection of bacteria. Moreover, we found 2974 genes expressed only in spleen of bighead carp and 3494 genes expressed only in spleen of silver carp, where these genes were mostly enriched in the same biological processes or pathways. These results provide a better understanding of the differences in resistance to some diseases by bighead carp and silver carp, and also facilitate the identification of candidate genes related to disease resistance.